1. Field of the Invention
This invention relates generally to the transdermal electrokinetic mass transfer of medication into a diseased tissue, and, more specifically, to a portable apparatus for the iontophoretic delivery of medication across the skin and incorporation of the medication into diseased tissues and blood vessels adjacent to the delivery site. The apparatus provides a new method for treating and managing diseases presenting cutaneous lesions.
2. Prior Art
Iontophoresis has been employed for several centuries as a means for applying medication locally through a patient""s skin and for delivering medicaments to the eyes and ears. The application of an electric field to the skin is known to greatly enhance the skin""s permeability to various ionic agents. The use of iontophoretic transdermal delivery techniques has obviated the need for hypodermic injection for many medicaments, thereby eliminating the concomitant problems of trauma, pain and risk of infection to the patient.
Iontophoresis involves the application of an electromotive force to drive or repel oppositely charged ions through the dermal layers into a target tissue. Particularly suitable target tissue include tissues adjacent to the delivery site for localized treatment or tissues remote therefrom in which case the medicament enters into the circulatory system and is transported to a tissue by the blood. Positively charged ions are driven into the skin at an anode while negatively charged ions are driven into the skin at a cathode. Studies have shown increased skin penetration of drugs at anodic or cathodic electrodes regardless of the predominant molecular ionic charge on the drug. This effect is mediated by polarization and osmotic effects.
Regardless of the charge of the medicament to be administered, a iontophoretic delivery device employs two electrodes (an anode and a cathode) in conjunction with the patient""s skin to form a closed circuit between one of the electrodes (referred to herein alternatively as a xe2x80x9cworkingxe2x80x9d or xe2x80x9capplicationxe2x80x9d or xe2x80x9capplicatorxe2x80x9d electrode) which is positioned at the delivered site of drug delivery and a passive or xe2x80x9cgroundingxe2x80x9d electrode affixed to a second site on the skin to enhance the rate of penetration of the medicament into the skin adjacent to the applicator electrode.
Recent interest in the use of iontophoresis for delivering drugs through a patient""s skin to a desired treatment site has stimulated a redesign of many of such drugs with concomitant increased efficacy of the drugs when delivered transdermally. As iontophoretic delivery of medicaments become more widely used, the opportunity for a consumer/patient to iontophoretically administer a transdermal dosage of medicaments simply and safely at non-medical or non-professional facilities would be desirable and practical. Similarly, when a consumer/patient travels, it would be desirable to have a personal, easily transportable apparatus available which is operable for the iontophoretic transdermal delivery of a medication packaged in a single dosage applicator. The present invention provides a portable iontophoretic medicament delivery apparatus and a unit-dosage medicament-containing applicator electrode which is disposable and adapted for use with the apparatus for self-administering medicament.
The present invention discloses a portable iontophoretic transdermal or transmucoscal medicament delivery apparatus and a unit dosage medicament applicator electrode adapted for use with the apparatus for the self-administration of a unit dose of a medicament into the skin. The apparatus is particularly suited for the localized treatment of herpes infections. Recurrent herpetic infections (fever blisters or herpes labialis) are very common and usually involve the mucocutaneous juncture. The established treatment for recurrent herpetic lesions (oral or genital) has been primarily supportive; including local topical application of anesthesia. Severe cases have been treated with systemic Acyclovir(copyright) (Zovirax Burroughs-Wellcome). Some cases the condition is managed with prophylactic long-term dosing administration with a suitable anitviral agent at great expense. Systemic treatment of acute herpetic flare-ups may reduce the normal 10-12 day course of cutaneous symptoms into a 6-8 day episode. Topical treatment of lesions with Acyclovir(copyright) has not been as effective as in vitro studies would suggest. A compound which is not presently available to clinicians but has demonstrated significant anti herpetic activity is 5-iodo-2 deoxyuridine (IUDR). Both of those agents have shown limited clinical efficacy when applied topically to the herpetic lesion. It is the present inventor""s contention that the limited efficacy of topical administration previously observed is, at least in part, due to the poor skin penetration of these medicaments when applied topically. The present invention provides improved transdermal delivery of these medicaments and demonstrates improved clinical results in the case of Herpes.
Oral Herpes (most commonly Herpes simplex I infection) as well as genital Herpes (usually Herpes Simplex II infection) afflict many people, cause discomfort, shame, and may contribute to more severe and costly illnesses such as cervical cancer, prostate cancer, and perinatal blindness from herpetic conjunctivitis. The present invention discloses a portable, user-friendly transdermal delivery device and a method for using the device with Acyclovir(copyright) [2-hydroxyethoxy(methyl)guanine (or similar antiviral agent) to greatly benefit these afflicted patients. The present inventor has constructed embodiments of this device and conducted human clinical trials which clearly demonstrate improved therapeutic efficacy using iontophoretically administered antiviral agents when compared to unassisted topical application of the agent.
It is an object of the present invention to provide an iontophoretic medicament delivery apparatus which is portable and operable for self-administration of medicament into the skin of a person.
It is another object of the present invention to provide an improved iontophoretic transdermal drub  drug delivery apparatus having a medicament-containing application electrode which disperses a single dosage and is disposable and non-reusable.
It is a feature of the present invention that the iontophoretic medicament delivery apparatus is easily maneuverable and operable when hand-held.
It is another feature of the present invention that the iontophoretic medicament delivery apparatus is battery powered and conveniently transported by a person.
It is a further feature of the present invention that the iontophoretic medicament delivery apparatus employs a tactile electrode which is in electrical contact with the skin of a user""s hand when the apparatus is held in the user""s hand, obviating the need for a separate grounding electrode connector or wire:
It is still another feature of the present invention that the iontophoretic medicament delivery apparatus is adapted to be operable with a disposable medicament containing applicator electrode which applicator electrode includes an absorbent, inert, non-corrosive portion containing a therapeutic agent.
It is yet another feature of the present invention to provide an embodiment of an iontophoretic transdermal delivery device wherein the disposable iontophoretic medicament-containing applicator electrode is adapted for releasable attachment to use with a hand-held base assembly housing a grounding electrode.
It is yet another feature of the present invention that the disposable iontophoretic medicament applicator electrode include indicator means operable for enabling a user to determine when the medicament within the removable applicator electrode has been released in delivery and/or depleted.
It is yet another feature of the present invention that the circuitry employed in the disposable iontophoretic medicament applicator include current limiting means operable for limiting the electrical current flowing between the surface of the applicator and the skin to less than about one milliampere per square centimeters of application electrode skin-contacting surface.
It is another advantage of the present invention that the iontophoretic medicament delivery apparatus employs a disposable application electrode which conducts the electrical current to the tissue through the solution in which the medicament is dissolved.
It is still another advantage of the present invention that the improved disposable iontophoretic medicament applicator is inexpensive, safe to use and greatly increases the therapeutic efficacy of a medicament administered thereby.
The apparatus in accordance with the present invention provides a means for topically administering medicament directly and with high efficiency into a diseased tissue thereby providing a novel method for treating clinical conditions presenting mucocutaneous symptoms and particularly mucocutaneous Herpes Simplex viral eruptions and sequelle associated therewith.
The above objects, features and advantages of the invention are realized by the improved monopolar iontophoretic medicament applicator which is easily transportable. The applicator employs a detachable medicament containing application electrode. The objects, features and advantages of the invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when it is taken in conjunction with the accompanying drawings wherein: